Patent Literature 1 discloses a detector array used in an X-ray imaging system. This detector array has a detector element that is provided on a glass substrate, a scintillator that is constituted of columnar crystals formed on the detector element, and a sheet that is disposed on the scintillator and reflects visible light. The scintillator and the sheet are sealed by a cover fixed to the glass substrate. For example, the cover and the glass substrate are sealed by a metal frame bonded using an epoxy sealant. The metal frame surrounds the scintillator away from the scintillator.